This invention relates to the field of heat exchangers, and more particularly to a molded plastic tube-in-tube heat exchanger, especially for vehicle engine oil cooling.
Tube-in-tube type heat exchangers are commonly used with vehicle and stationary engines for oil cooling, and are also found on auxiliary generators and in industrial and chemical process plants. Tube-in-tube type heat exchangers are well known, and have taken a variety of configurations in the past. Some examples of heat exchangers in the prior art are shown in the following patents:
Graham, U.S. Pat. No. 2,341,319, Habdas, U.S. Pat. No. 4,086,959, and Shearer, U.S. Pat. No. 4,218,999, each discloses two coaxial tubes with a helical fin turbulator enclosed within the annular space between the tubes.
McCandless, U.S. Pat. No. 4,924,838, and Roeder, U.S. Pat. No. 3,566,615, each depict two coaxial tubes, one or both of which are formed into a helical turbulator enclosed within the annular space between the tubes.
In the above-described inventions, there is no elastomer seal between the inner and outer tubes. The housing is not plastic, and hence is subject to corrosion. The parts must be assembled axially, then sealed by expanding or welding. The process is labor intensive, and the product is subject to leakage. The inlets and outlets are not molded integral with the housing, but are welded on. The turbulator is not molded integral with the housing, but is formed of metal, then threaded into grooves or welded on. None of the prior-art devices has a mounting bracket molded integral with the housing. All of the above-described devices are assembled axially in a complicated process that is difficult to seal.
Accordingly, there is a need to provide a tube-in-tube type heat exchanger that has a plastic housing to preclude corrosion.
There is a further need to provide a heat exchanger of the type described and wherein the housing is split lengthwise for fast and easy assembly.
There is a yet further need to provide a heat exchanger of the type described and that has an elastomer seal between the inner and outer tubes, for easy assembly and positive sealing.
There is a still further need to provide a heat exchanger of the type described and wherein all of the inlets and outlets are molded integral with the housing.
There is another need to provide a heat exchanger of the type described and wherein the turbulator is molded integral with the housing.
There is yet another need to provide a heat exchanger of the type described and that transfers heat through a metal for efficient heat flow.
There is still another need to provide a heat exchanger of the type described and that has a mounting bracket molded integral with the housing.
There is an additional need to provide a heat exchanger of the type described and that can be manufactured cost-effectively in large quantities of high quality.